Role of the Interdomain Hinge of Flavocytochrome b2 in Intra- and Inter-Protein Electron Transfer

Biochemistry ◽  
1994 ◽  
Vol 33 (17) ◽  
pp. 5115-5120 ◽  
Author(s):  
R. Eryl Sharp ◽  
Patricia White ◽  
Stephen K. Chapman ◽  
Graeme A. Reid
Keyword(s):  
Electron Transfer ◽  
Flavocytochrome B2 ◽  
Protein Electron Transfer

scholarly journals Modulation of flavocytochrome b2 intraprotein electron transfer via an interdomain hinge region

1996 ◽  
Vol 316 (2) ◽  
pp. 507-513 ◽  
Author(s):  
R. Eryl SHARP ◽  
Stephen K. CHAPMAN ◽  
Graeme A. REID
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Lactate Dehydrogenase ◽  
Structural Integrity ◽  
Hinge Region ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Lactate Dehydrogenase Activity ◽  
Flavocytochrome B2

The two domains of flavocytochrome b2 are connected by a typical hinge peptide. To probe the role of the hinge in modulating the efficiency of intraprotein electron transfer between these two domains, a number of mutant enzymes with truncated hinge regions were previously constructed and characterized [Sharp, Chapman and Reid (1996) Biochemistry 35, 891–899]. In the present study two mutant enzymes with elongated hinge regions have been constructed (HI3 and HI6) to further our understanding of the controlling influence of hinge length and primary structure on intraprotein electron transfer. Modification of the hinge had little effect on the lactate dehydrogenase activity of the enzyme, as was evident from steady-state experiments using ferricyanide as electron acceptor and from pre-steady-state experiments monitoring flavin reduction. However, the hinge insertions lowered the enzyme's effectiveness as a cytochrome c reductase. This effect results from a defect at the first interdomain electron-transfer step (FMNH2 → haem electron transfer), where the rate constants for haem reduction in HI3 and HI6 were 50-and 100-fold lower than the corresponding value for the wild-type enzyme. Preservation of structural integrity within the hinge region is apparently essential for efficient intraprotein electron transfer.

Advantageous Role of Ir0 Supported on TiO2 Nanosheets in Photocatalytic CO2 Reduction to CH4: Fast Electron Transfer and Rich Surface Hydroxyl Groups

2021 ◽  
Vol 13 (5) ◽  
pp. 6219-6228
Author(s):  
Kunlin Tang ◽  
Zhiqiang Wang ◽  
Weixin Zou ◽  
Hongyu Guo ◽  
Yuchao Wu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fast Electron ◽  
Co2 Reduction ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Tio2 Nanosheets

scholarly journals Conversion of Methanol on Rutile TiO2 (110) and Tungsten Oxide Clusters: 2. The Role of Defects and Electron Transfer in Bifunctional Oxidic Photocatalysts

2021 ◽  
Author(s):  
Lars Mohrhusen ◽  
Jessica Kräuter ◽  
Katharina Al-Shamery
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Metal Oxide ◽  
Tungsten Oxide ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Organic P ◽  
Rutile Tio2 ◽  
Metal Oxide Surfaces

The photochemical conversion of organic compounds on tailored transition metal oxide surfaces by (UV) irradiation has found wide applications ranging from the production of chemicals to the degradation of organic...

scholarly journals Key role of antibonding electron transfer in bonding on solid surfaces

2019 ◽  
Vol 3 (9) ◽  
Author(s):  
Liping Yu ◽  
Qimin Yan ◽  
Adrienn Ruzsinszky
Keyword(s):  
Electron Transfer ◽  
Solid Surfaces

Improving peroxymonosulfate activation by copper ion-saturated adsorbent-based single atom catalysts for the degradation of organic contaminants: electron-transfer mechanism and the key role of Cu single atoms

2021 ◽  
Author(s):  
Jingwen Pan ◽  
Baoyu Gao ◽  
Pijun Duan ◽  
Kangying Guo ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Organic Contaminants ◽  
High Salinity ◽  
Copper Ion ◽  
Single Atom ◽  
Electron Transfer Mechanism ◽  
Persulfate Oxidation ◽  
Single Atoms ◽  
Oxidation Technology

Nonradical pathway-based persulfate oxidation technology is considered to be a promising method for high-salinity organic wastewater treatment.

scholarly journals On the role of non-diagonal system–environment interactions in bridge-mediated electron transfer

2020 ◽  
Vol 153 (18) ◽  
pp. 185101
Author(s):  
Nirmalendu Acharyya ◽  
Roman Ovcharenko ◽  
Benjamin P. Fingerhut
Keyword(s):  
Electron Transfer ◽  
System Environment ◽  
Diagonal System ◽  
Mediated Electron Transfer

scholarly journals Theoretical Study on the Photo-Oxidation and Photoreduction of an Azetidine Derivative as a Model of DNA Repair

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2911
Author(s):  
Miriam Navarrete-Miguel ◽  
Antonio Francés-Monerris ◽  
Miguel A. Miranda ◽  
Virginie Lhiaubet-Vallet ◽  
Daniel Roca-Sanjuán
Keyword(s):  
Electron Transfer ◽  
Energy Barrier ◽  
Ring Opening ◽  
Dna Lesions ◽  
Barrier Heights ◽  
Dna Lesion ◽  
Electron Reduction ◽  
The Stability ◽  
Electron Transfer Processes

Photocycloreversion plays a central role in the study of the repair of DNA lesions, reverting them into the original pyrimidine nucleobases. Particularly, among the proposed mechanisms for the repair of DNA (6-4) photoproducts by photolyases, it has been suggested that it takes place through an intermediate characterized by a four-membered heterocyclic oxetane or azetidine ring, whose opening requires the reduction of the fused nucleobases. The specific role of this electron transfer step and its impact on the ring opening energetics remain to be understood. These processes are studied herein by means of quantum-chemical calculations on the two azetidine stereoisomers obtained from photocycloaddition between 6-azauracil and cyclohexene. First, we analyze the efficiency of the electron-transfer processes by computing the redox properties of the azetidine isomers as well as those of a series of aromatic photosensitizers acting as photoreductants and photo-oxidants. We find certain stereodifferentiation favoring oxidation of the cis-isomer, in agreement with previous experimental data. Second, we determine the reaction profiles of the ring-opening mechanism of the cationic, neutral, and anionic systems and assess their feasibility based on their energy barrier heights and the stability of the reactants and products. Results show that oxidation largely decreases the ring-opening energy barrier for both stereoisomers, even though the process is forecast as too slow to be competitive. Conversely, one-electron reduction dramatically facilitates the ring opening of the azetidine heterocycle. Considering the overall quantum-chemistry findings, N,N-dimethylaniline is proposed as an efficient photosensitizer to trigger the photoinduced cycloreversion of the DNA lesion model.

scholarly journals The importance of the interdomain hinge in intramolecular electron transfer in flavocytochrome b2

1993 ◽  
Vol 291 (1) ◽  
pp. 89-94 ◽  
Author(s):  
P White ◽  
F D C Manson ◽  
C E Brunt ◽  
S K Chapman ◽  
G A Reid
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome C ◽  
Kinetic Properties ◽  
Stopped Flow ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Cytochrome C Reductase ◽  
Flavocytochrome B2 ◽  
Cytochrome C Reduction

The two distinct domains of flavocytochrome b2 (L-lactate:cytochrome c oxidoreductase) are connected by a typical hinge peptide. The amino acid sequence of this interdomain hinge is dramatically different in flavocytochromes b2 from Saccharomyces cerevisiae and Hansenula anomala. This difference in the hinge is believed to contribute to the difference in kinetic properties between the two enzymes. To probe the importance of the hinge, an interspecies hybrid enzyme has been constructed comprising the bulk of the S. cerevisiae enzyme but containing the H. anomala flavocytochrome b2 hinge. The kinetic properties of this ‘hinge-swap’ enzyme have been investigated by steady-state and stopped-flow methods. The hinge-swap enzyme remains a good lactate dehydrogenase as is evident from steady-state experiments with ferricyanide as acceptor (only 3-fold less active than wild-type enzyme) and stopped-flow experiments monitoring flavin reduction (2.5-fold slower than in wild-type enzyme). The major effect of the hinge-swap mutation is to lower dramatically the enzyme's effectiveness as a cytochrome c reductase; kcat. for cytochrome c reduction falls by more than 100-fold, from 207 +/- 10 s-1 (25 degrees C, pH 7.5) in the wild-type enzyme to 1.62 +/- 0.41 s-1 in the mutant enzyme. This fall in cytochrome c reductase activity results from poor interdomain electron transfer between the FMN and haem groups. This can be demonstrated by the fact that the kcat. for haem reduction in the hinge-swap enzyme (measured by the stopped-flow method) has a value of 1.61 +/- 0.42 s-1, identical with the value for cytochrome c reduction and some 300-fold lower than the value for the wild-type enzyme. From these and other kinetic parameters, including kinetic isotope effects with [2-2H]lactate, we conclude that the hinge plays a crucial role in allowing efficient electron transfer between the two domains of flavocytochrome b2.

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